Transwitch Corporation

Rakesh Kumar Malik

Dinesh Gupta

Dev Shankar Mukherjee

Harsh Chilwal

Write logic and read logic are coupled to SDRAM and a frame status table. VCG members are written into SDRAM by the write logic and an entry (based on the MFI and SQ) in the frame status table is maintained by the write logic for each member. The read logic scans the frame status table to identify the earliest frame number for which data is available in SDRAM. Based on the frame status and the address pointer offset, the read logic maintains a state table entry for each VCG member and a state for each VCG. According to the preferred embodiment, the read logic is provided in two parts separated by a temporary buffer. The first part of the read logic performs the functions described above and writes chunk data into the temporary buffer. The second part of the read logic reads byte data from the temporary buffer according to a selectable leak rate.

Methods and apparatus for deskewing VCAT/LCAS members

Combined hardware and software processing is applied in an end node of the network which includes mapping/demapping and deskewing. Most of the LCAS procedure is implemented in software so that it can be modified easily. Some of the procedure is implemented in hardware to meet stringent timing requirements. In particular, the handshaking protocol is implemented in software and the procedure for actually changing of the link capacity in response to the handshaking is implemented in hardware. The hardware and software communicate via a shared memory which includes a receive packet FIFO, receive control and status registers, a transmit packet FIFO, transmit control and status registers, and a transmit time slot interchange table.

Combined hardware and software implementation of link capacity adjustment scheme (LCAS) in SONET (synchronous optical network) virtual concatenation (VCAT)

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New Delhi, India

Rakesh Kumar Malik